The continuous increase in Internet users as well as the development of new network technologies, such as multi-homing technology, traffic engineering, policy routing, and virtual private network (VPN) technology and so on, result in an increase in the scale of the router's routing table, especially, the dramatic increase of the Border Gateway Protocol (BGP) routing table in the Default-Free Zone (DFZ), and the issue of scalability of the routing table scale is increasingly becoming the bottleneck in the current network development.
This issue was first raised by the Internet Architecture Board (IAB) in the routing and address technology seminar in the Internet Engineering Task Force (IETF) meeting in October 2006, thereafter, for the problem that the scale of the DFZ routing table is too large, a number of solutions are put forward, and most of these solutions are based on one common idea: the Locator/ID Split, that is, splitting the dual property of the identity and routing locator of IP address, using the Endpoint Identity (EID) to identify one host device and using the Routing Locator (RLOC) for route addressing and forwarding data packet.
The Locator ID Separation Protocol (LISP) is a network-based locator and identity separation protocol, and its basic idea is:                (1) the existing IP address is divided into the endpoint identity (EID) and the routing locator (RLOC), and the concept of the Tunnel Routers is introduced, and the tunnel routers includes the Ingress tunnel Router (ITR) and the Egress Tunnel Router (ETR);        (2) the host does not change, and the IP address of the data sent by host is represented by the EID, and the transport of said data packet in the network depends on the RLOC information, and the packet is forwarded by looking up the RLOC routing table;        (3) the ITR is responsible for data packet encapsulation and searching for mapping, that is, searching out the corresponding RLOC information according to the destination EID information in the data packet, and encapsulating the searched-out RLOC information in the data packet header;        (4) the ETR is responsible for de-capsulating and then forwarding the data packet to the destination host when receiving a data packet.        
The LISP data encapsulation and forwarding use an IP-in-IP method, and the source IP address and destination IP address of outer IP packet header are RLOC addresses and are used to forward the data packet in the network, and the source IP address and the destination IP address of the inner layer IP packet header are the endpoint identities (EIDs), the data packet encapsulation formats are respectively shown in FIGS. 1 and 2, wherein, FIG. 1 is the IP-in-IP encapsulation format of an IPv4 packet and FIG. 2 is the IP-in-IP encapsulation format of an IPv6 packet.
FIG. 3 shows the data forwarding method in the existing LISP network. After the ITR receives an IP packet from the host, according to the destination EID address in the packet, the ITR searches for the corresponding RLOC address in the local mapping cache, and under normal circumstances, the ITR's local cache saves the EID and RLOC mapping, and if the EID and RLOC mapping is not searched out in the ITR local cache, it needs to query the mapping system and save the mapping in the local mapping cache. The ITR encapsulates the IP packet header outside the host IP packet, and encapsulates the searched-out RLOC address as the destination IP address of the outer IP packet. During the transmission process in the IP backbone network, the forwarding of data packets only depends on the outer destination RLOC address for looking up the routing table, and after the data packet reaches the ETR, the ETR peels off the outer IP packet header and forwards the inner IP packet to the destination host.
The deployment of the LISP technology in the existing IP network needs to form an edge of a tunnel router, and it needs to upgrade the protocol stack of the routers on the edge to form an ITR/ETR, so as to implement the IP-in-IP data encapsulation and packet forwarding of the LISP, and other routers are not affected. Of course, the ITR/ETR can be newly deployed to implement the LISP. Since the Multiprotocol Label Switching (MPLS) technology has basically been deployed in the current mainstream IP networks in order to achieve the VPN service, traffic engineering, and Quality of Service (QoS) and other functions, and the label switched path (LSP) is used to achieve fast forwarding. Therefore, it is considered to use the label switching technology function in the MPLS network to achieve the fast forwarding of the packet and utilize the advantages of MPLS in aspects of VPN services, traffic engineering and QoS and so on during the deployment of LISP technology.
Currently, there is no corresponding solution to be put forward in the prior art to solve the problems about how to effectively deploy the LISP technology in the MPLS network and how to implement the encapsulation and forwarding of packets.